Add flash addr for H743ZI (not tested yet)

Author: multiplemonomials

mbed_app.json5

@@ -124,6 +124,7 @@
 
             // Since STM32H743 boards have no external block device, keep everything in the MCU flash.
             "app.secondary-slot-in-flash": true,
+            "app.secondary-slot-flash-start-addr": "0x100000",
 
             // Slot size can be as big as 896k, since we need to reserve the first flash sector for the bootloader
             // and the last flash sector for scratch space